a. Field of Invention
The invention relates generally to vehicle structural component assembly, and, more particularly, to a method of bonding and sealing vehicle structural component joints.
b. Description of Related Art
As is known in the art, one method of joining automotive structural or bodyside components is to bond the components by an adhesive having a predetermined bending and torsional stiffness. While known adhesives used for such bonding provide adequate bending and torsional stiffness properties, such adhesives lack the sealing properties for air leakage or water intrusion. Therefore, a secondary sealing step is required for meeting air leakage and water intrusion requirements.
For example, while in a coupe automobile, bending stiffness requirements may be on the order of 75,000 lbf/in and torsional stiffness requirements may be on the order of 13,500 ft-lbf/deg, in convertible automobiles, the bending stiffness requirements may be on the order of 32,000 lbf/in and torsional stiffness requirements may be on the order of 6,000 ft-lbf/deg. While the noted bending and torsional stiffness requirements in such coupe and convertible automobiles may be different, in order to meet production costs and volumetric requirements, since the noted types of automobiles often share a variety of structural and bodyside components, the adhesives and sealers used are also generally common to both types of automobiles. Thus it is often difficult to change the type of adhesives and sealers used in different types of automobiles, without significantly increasing the design and production costs, running the risk of failing to meet the noted bending and torsional stiffness or sealing requirements, and/or requiring use of secondary structural reinforcement for meeting such requirements.
Yet further, from a production viewpoint, the steps of bonding and sealing structural and bodyside component joints generally require the first step of adhesive application. Thereafter, upon application of sufficient pressure for adhesive bonding and/or elapse of sufficient time for adhesive curing, a sealer which expands approximately 150% of its original application layer thickness may be applied to cover the adhesive bond area. Thus when used in combination, the noted adhesive and sealer layers provide adequate bending and torsional stiffness, and sealing properties. Nevertheless, as readily evident, use of the separate adhesive and sealer layers in a fast-paced automotive assembly environment are prohibitive both from a cost and production time requirement perspective.
Such an exemplary bonding and sealing method is disclosed for example in U.S. Patent App. No. 2004/0046423 to Wieber. Referring to FIGS. 1 of Wieber, there is disclosed a roof (12) including roof panel (16), and body panel (14), which may be a door side panel, which are interconnected via flanges (58, 26). A structural adhesive material (74) extends along the side edges (22, 54) respectively of the outer roof panel (16) and the outer body panel (14). Further, a strip (76) of sealant material is likewise provided and extends the side edges (22, 54) respectively of the outer roof panel (16) and the outer body panel (14).
Thus, as discussed above, Wieber discloses a bonding and sealing method which requires application of a first structural adhesive material and a second sealing layer for meeting the structural strength and sealing requirements in an automobile. Wieber also discloses the use of the adhesive/sealant combination in a roof/door panel area, which is also known in the art. Yet further, whereas Wieber discloses the adhesive material may be flowable and/or expandable upon the application of heat, Wieber nevertheless requires the use of both adhesive and sealant layers for meeting structural strength and sealing requirements.
It would therefore be of benefit to provide a method of bonding and sealing automotive structural and bodyside components without significantly increasing the costs associated with such processes, and without significantly affecting the performance characteristics of the joints, regardless of the types of automobiles. It would also be of benefit to provide a method of bonding and sealing automotive structural and bodyside components in a single-step process, without the need for separately bonding and sealing component joints.